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measurement of sea level

…a satellite equipped with a radar altimeter can be used to sound from the satellite’s instantaneous position to the sea. The accuracy with which the sea surface can be reconstructed depends on how precisely the satellite orbit is known, and the reduction of the dynamic effects on the sea surface…

ocean sensing

Satellite-borne radar altimeters have proved to be especially useful. A radar system of this type can determine the distance between the satellite and the sea surface to an accuracy of better than 10 centimetres by measuring the time it takes for a transmitted pulse of radio…